Spare Change

A recent survey, which included inspections of more than 7,000 vehicles revealed that more than 11 percent had at least one bald tire, which can increase the risk of a crash particularly in wet weather conditions. Compounding this issue are the colder temperatures that occur during the fall and winter months.

Tens of millions of motorists take to the road for vacation travel every year, consequently over a million motorists could be at risk by driving on bald tires. Additional alarming statistics revealed in a national motorist phone survey found that 64% of car owners did not know how to check tread depth and 9% never check tread depth.

These surveys were sponsored by the Rubber Manufacturers Association (RMA), the national trade association of tire manufacturers in the U.S. RMA is urging motorists to regularly check tire tread depth and replace worn out tires before they become a serious safety risk.

In this bad economy, drivers may be delaying necessary vehicle maintenance to save costs. That delay may cost you more dearly if worn out tires lead to a crash with injuries or fatalities. Your tires literally keep your vehicle attached to the road. Bald tires are dangerous because they cannot grip the road properly; they increase stopping distances and can contribute to skidding or loss of vehicle control.

Penny TestChecking tread depth is simple and only costs a penny. To do the “penny test,” take a penny; insert Abe Lincoln’s head upside down into the tread. If you can see all of his head, your tire is 2/32" deep or less and should be replaced. Tires also have tread wear indicators known as "wear bars" built into them. These are indicators that appear when you have worn your tread down to the limit. These indicators are raised sections spaced intermittently in the bottom of the tread grooves. When they appear "even" with the outside of the tread, it's time for tire replacement.

4/32" Quarter TestIf rain and wet roads are a concern, you should consider replacing your tires when they reach approximately 4/32" of remaining tread depth. Water can't be compressed, so you need enough tread depth to allow the rain to escape through the tire's grooves. If the water can't escape fast enough, your vehicle's tires will be forced to hydroplane (float) on top of the water, losing traction and increasing stopping distances. It costs a little more to use a coin to test for 4/32". Take a quarter; insert George Washington’s head upside down into the tread in several locations across the tire. If you can see all of his head, your tire is 4/32nds of an inch deep or less and should be replaced, to maintain the best wet traction. To see this illustrated under real life conditions, watch "Panic Stopping: How Much Tread Depth Do You Need?" and read "What Honest Abe Doesn't Tell You About Minimum Tread Depths."

6/32' Penny TestIf you drive an all-season tire in winter weather conditions (snow/ice), then tread depth is even more critical. The average all-season (M&S) tire will lose effectiveness in winter conditions below 6/32". You can also measure this tread depth with with a penny. Place a penny into several tread grooves across the tire. If the top of the Lincoln Memorial is always covered by the tread you have more that 6/32" of tread remaining. To learn more about tread depth and tire replacement criteria, read "When Should I Replace My Tires?"

Dill Digital Tread Depth GaugeIf you:
  • Regularly rotate your own tires
  • Don't usually carry change
  • Have several sets of tires for multiple vehicles.
  • Want greater accuracy than you can get with coins might want to look at a more precise measuring device.
Dill's Digital Tread Depth Gauge displays tread depths in millimeters, inches and fractions at 1/32 increments. The gauge's large LCD display makes it easy to read. Its zero function allows you to zero the gauge at any point making readings quick and accurate.

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